This invention relates generally to land mobile radios, and more particularly, to a system for providing land mobile radio content using a cellular data network.
Land mobile radios may be used to provide communication between different mobile units, for example, land mobile radios. Land mobile radio band communication, for example, public safety radio communication (e.g., police, fire department, etc.) is generally available within the VHF, UHF, 700 MHz and 800 MHz frequency bands. Part of each of these frequency bands is allocated by the Federal Communications Commission (FCC) for public safety communication services and are also referred to as Public Safety Frequency Bands. These communications also may be provided using private land mobile radio services (PLMRS).
Cellular networks also provide communication between different mobile users, for example, cellular telephones. These cellular networks continue to be enhanced and allow for a continually growing set of applications to be made available to users. For example, these cellular networks now provide Push-to-talk (PTT) services that provide direct connect capabilities. Thus, a cellular phone user may request a direct connect communication link with another cellular phone user in a two way radio or “walkie talkie” type communication. As another example, these cellular networks provide high-speed data services, such as, for example, General Packet Radio Service (GPRS), Enhanced Data Rates for GSM Evolution (EDGE), Evolution Data Optimized (EV-DO) and Universal Mobile Telephone Service (UMTS).
Known systems providing enhanced services or features, such as enhanced calling or voice features, which may be used, for example, for mission critical wireless networks, such as public safety applications, use commercial cellular services, such as PTT services, to augment and or replace traditional LMR systems. These systems are provided using specialized gateway equipment that enables certain interoperability capabilities between an LMR system and a cellular network with PTT capabilities by translating and/or transforming the data or voice communications to be communicated between the networks, for example from an LMR network to a cellular network.
In the Land Mobile Radio (LMR) industry, new technologies are also being provided, including the use of digital communication instead of analog communication. Additionally, LMR systems are now using packet switching instead or circuit switching, for example, using Internet Protocol (IP) and Voice Over IP (VoIP) to enable construction of highly scalable and cost effective LMR networks.
Traditionally, LMR networks have been used to provide mission critical applications such as public safety communications. In addition to providing a very high level of system availability, LMR networks are primarily designed to support PTT services, such as a dispatch mode of operation. In LMR networks, PTT services are often configured for operation in connection with defined or predetermined workgroups. For communication purposes, workgroups further may be organized into talk groups. In operation, radio users and dispatchers key up PTT on a talk group. The LMR network is configured such that all members of the workgroup receive the communications being broadcast on a particular talk group.
In addition to PTT services, LMR networks also may contain a feature set to support a variety of mission critical applications. For example, in public safety applications, LMR networks provide a number of emergency services, for example, to allow a user in trouble to invoke an emergency alerting capability with a single button press. LMR Networks also provide a variety of priority and preemption services. These services provide system access to the most important communications when there are insufficient resources or inadequate system capacity to handle all the concurrent PTT calls.
These LMR systems use specialized LMR airlink protocols to communicate wirelessly between LMR radios and LMR infrastructure. Known systems for providing LMR features or communications, such as PTT, over a public network, for example, a public cellular network, translate or transform the data or communications, for example, using VoIP protocols in the terminals/radio devices. Thus, these systems require additional controls and equipment to implement the interconnectivity, thereby adding complexity and cost to the overall system.